Added test for BaseRiskCalculator.assets_at
Added test for BaseRiskCalculator.assets_at


Former-commit-id: 854090ecec94c4c32e8f7183778cbfffa1c29df0 [formerly a716134fb8e09413240e87ad5ce1a8e69e947cf4]
Former-commit-id: b9f9a5c1b22b71d1586ae61f3fd8738b0415ec97
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine